Parameters of abyss-pe¶

name, JOB_NAME

The name of this assembly. The resulting scaffolds will be stored in ${name}-scaffolds.fa.

in

input files. Use this variable when assembling data from a single library.

lib

a quoted list of whitespace-separated paired-end library names. Use this variable when assembling data from multiple paired-end libraries. For each library name in lib, the user must define a variable on the command line with the same name, which indicates the read files for that library. See EXAMPLES below for a concrete example of usage.

pe

list of paired-end libraries that will be used only for merging unitigs into contigs and will not contribute toward the consensus sequence.

mp

list of mate-pair libraries that will be used for scaffolding. Mate-pair libraries do not contribute toward the consensus sequence.

long

list of long sequence libraries that will be used for rescaffolding. long sequence libraries do not contribute toward the consensus sequence.

se

files containing single-end reads

a

maximum number of branches of a bubble [2]

b

maximum length of a bubble (bp) [""]
abyss-pe has two bubble popping stages. The default limits are 3*k bp for ABYSS and 10000 bp for PopBubbles.

c

minimum mean k-mer coverage of a unitig [sqrt(median)]

d

allowable error of a distance estimate (bp) [6]

e

minimum erosion k-mer coverage [round(sqrt(median))]

E

minimum erosion k-mer coverage per strand [1 if sqrt(median) > 2 else 0]

j

number of threads [2]

k

size of a k-mer (when K is not set) or the span of a k-mer pair (when K is set)

K

size of a single k-mer in a k-mer pair (bp)

l

minimum alignment length of a read (bp) [40]

m

minimum overlap of two unitigs (bp) [k-1]

n

minimum number of pairs required for building contigs [10]

N

minimum number of pairs required for building scaffolds [n]

p

minimum sequence identity of a bubble [0.9]

q

minimum base quality when trimming [3]
Trim bases from the ends of reads whose quality is less q.

Q

minimum base quality [0]
Mask all bases of reads whose quality is less than Q as `N'.

s

minimum unitig size required for building contigs (bp) [1000]
The seed length should be at least twice the value of k. If more sequence is assembled than the expected genome size, try increasing s.

S

minimum contig size required for building scaffolds (bp) [1000-10000]

SS

SS=--SS to assemble in strand-specific mode
Requires that all libraries are strand-specific RNA-Seq libraries. Assumes that the first read in a read pair is reversed WRT the transcripts sequenced.

t

maximum length of blunt contigs to trim [k]

v

v=-v to enable verbose logging

np, NSLOTS

the number of processes of an MPI assembly

mpirun

the path to mpirun

aligner

The program to use to align the reads to the contigs [map].
Permitted values are: map, kaligner, bwa, bwasw, bowtie, bowtie2, dida. See the DIDA section below for further info on the dida option.

cs

convert colour-space contigs to nucleotide contigs following assembly

Options of make¶

-n, --dry-run

Print the commands that would be executed, but do not execute them.

Make targets for abyss-pe¶

default

Equivalent to `scaffolds scaffolds-dot stats'.

unitigs

Assemble unitigs.

unitigs-dot

Output the unitig overlap graph.

pe-sam

Map paired-end reads to the unitigs and output a SAM file. SAM file will only contain reads mapping to different contigs, and the read ID, sequence and quality strings will be replaced with '*' characters.

pe-bam

Map paired-end reads to the unitigs and output a BAM file. BAM file will only contain reads mapping to different contigs, and the read ID, sequence and quality strings will be replaced with '*' characters.

pe-index

Generate an index of the unitigs used by abyss-map.

contigs

Assemble contigs.

contigs-dot

Output the contig overlap graph.

mp-sam

Map mate-pair reads to the contigs and output a SAM file. SAM file will only contain reads mapping to different contigs, and the read ID, sequence and quality strings will be replaced with '*' characters.

mp-bam

Map mate-pair reads to the contigs and output a BAM file. BAM file will only contain reads mapping to different contigs, and the read ID, sequence and quality strings will be replaced with '*' characters.

mp-index

Generate an index of the contigs used by abyss-map.

scaffolds

Assemble scaffolds.

scaffolds-dot

Output the scaffold overlap graph.

scaftigs

Break scaffolds and generate AGP file.

long-scaffs

Rescaffold using RNA-Seq assembled contigs.

long-scaffs-dot

Output the RNA scaffold overlap graph.

stats

Display assembly contiguity statistics.

clean

Remove intermediate files.

version

Display the version of abyss-pe.

versions

Display the versions of all programs used by abyss-pe.

help

Display a helpful message.

DIDA-related abyss-pe parameters¶

DIDA_MPIRUN

The `mpirun` command used to run DIDA jobs.

DIDA_RUN_OPTIONS

Runtime options such as number of threads per MPI rank and values for environment variables (e.g. PATH, LD_LIBRARY_PATH). Run `abyss-dida --help` for a list of available options.

DIDA_OPTIONS

Options that are passed directly to the DIDA binary. For example, this can be used to control the minimum alignment length threshold. Run `dida-wrapper --help` for a list of available options.

MPI COMPATIBILITY¶

Due to its use of multi-threading, DIDA has known deadlocking issues with OpenMPI. Using the MPICH MPI library is strongly recommended when running assemblies with DIDA. Testing was done with MPICH 3.1.3, compiled with --enable-threads=funneled.

EXAMPLE¶

The recommended runtime configuration for DIDA is 1 MPI rank per machine and 1 thread per CPU core. For example, to run an assembly across 3 cluster nodes with 12 cores each, do:

abyss-pe k=64 name=ecoli in='reads1.fa reads2.fa' aligner=dida DIDA_RUN_OPTIONS='-j12' DIDA_MPIRUN='mpirun -np 3 -ppn 1 -bind-to board'

This example uses the MPICH command line options for `mpirun`. Here, `-np 3` indicates the number of MPI ranks, `-ppn 1` indicates the number of MPI ranks per "node", and `-bind-to board` defines a "node" to be a motherboard (i.e. a full machine).

Scheduler integration¶

ABySS integrates well with cluster job schedulers, such as:
* SGE (Sun Grid Engine)
* Portable Batch System (PBS)
* Load Sharing Facility (LSF)
* IBM LoadLeveler

The SGE environment variables JOB_NAME, SGE_TASK_ID and NSLOTS may be used to specify the parameters name, k and np, respectively, and similarly for other schedulers.

One paired-end library¶

abyss-pe k=64 name=ecoli in='reads1.fa reads2.fa'

Multiple paired-end libraries¶

abyss-pe k=64 name=ecoli lib='lib1 lib2' \
lib1='lib1_1.fa lib1_2.fa' lib2='lib2_1.fa lib2_2.fa' \
se='se1.fa se2.fa'

Paired-end and mate-pair libraries¶

abyss-pe k=64 name=ecoli lib='pe1 pe2' mp='mp1 mp2' \
pe1='pe1_1.fa pe1_2.fa' pe2='pe2_1.fa pe2_2.fa' \
mp1='mp1_1.fa mp1_2.fa' mp2='mp2_1.fa mp2_2.fa' \
se='se1.fa se2.fa'

Including RNA-Seq assemblies¶

abyss-pe k=64 name=ecoli lib=pe1 mp=mp1 long=long1 \
pe1='pe1_1.fa pe1_2.fa' mp1='mp1_1.fa mp1_2.fa' \
long1=long1.fa

MPI¶

abyss-pe np=8 k=64 name=ecoli in='reads1.fa reads2.fa'

SGE¶

qsub -N ecoli -t 64 -pe openmpi 8 \
abyss-pe n=10 in='reads1.fa reads2.fa'